Insulator for electron discharge devices



May 21, 1940. J. GLAUBER 2,201,289

INSULATOR FOR ELECTRON DISCHARGE DEVICES Filed Nov. 8, less INVENTOR J 64 905.67?

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ATTORN EY Patented May 21, 1940 UNITED STATES INSULATOR FOR ELECTRON DISCHARGE DEVICES John Glauber, West Orange, N. J., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 8, 1938, Serial No. 239,493

7 Claims.

My invention relates to discharge devices and especially to the supports for the electrodes in such discharge devices.

An object of the invention is to provide an insulating support that will maintain a long creepage distance between the electrode standards supported thereon.

Other objects and advantages of my invention will be apparent from the following description and drawing, in which:

Fig. l is a view, partly in elevation and partly in cross-section, of an electrode assembly incorporated in my invention.

Fig. 2 is a View on lines IIII of Fig. 1.

Fig. 3 is a view similar to Fig. 2, illustrating the shortened creepage distance on insulators of the prior art.

Fig, 4 is an enlarged view on lines IV-IV of Fig. 1.

Fig. 5 is a perspective view of the top insulator in Fig. 1.

One of the problems in dealing with discharge devices is the fact that after many hours of operation, there may be a leakage of electricity from one electrode to the other. This leakage is caused by particles of matter impinging upon the insulating region about the electrode standard or by metal vapor condensing thereon and providing an ever increasing amount of conducting spots on the insulating space between the electrode leads or standards. Finally, these particles or condensed metal vapor become sufiiciently dense across the surface of the insulators to provide a path for the electricity to leak from a conductive standard having a high potential across the insulating surface by means of these particles to the electrode having a less positive potential value.

It is specifically an object of my invention to maintain an insulating surface on the insulating supports for electrodes that will be practically free of the usual sputtered material or condensed vapor and thus prevent the creepage across the surface of the insulator.

My invention has special value in connection with multiple electrode devices and I have chosen a typical screen-grid electrode assembly as illustrated in Fig. l to disclose a preferred embodiment of my invention. Other types of a more or less number of electrodes could have been chosen for such illustration. The special value of my invention with tubes having a multitude of electrodes is because space can be utilized to the best advantage, especially when the tube is to be placed within the so-called midget or table type of radio, and yet insulation is maintained constantly between the leads of the various electrodes.

The electrodes illustrated in Fig. 1 comprise the well known cathode In, control grid H surrounding this cathode, a screen grid l2 enclosing the cathode and control grid, and an anode [3 enclosing the other electrode. The cathode I0 is usually of small diameter wire supported on the hooks l4 resiliently mounted on the springs I5. The cathode is the common M-shaped form which utilizes two such resiliently mounted hooks at the top and having the two ends and central portion attached to three standards l6, l1, and IS. The control grid II comprises a spirally wound wire on at least one, preferably two or more, conducting and supporting standards I9 and 2B. The screen grid 12 likewise preferably comprises a spirally wound wire on the conducting standards 2| and 22. The anode I3 is preferably of sheet material enclosing the other electrodes.

These standards for the electrodes are supported at the top and bottom by two longitudinally extending insulators 23 and 24. Insulators have been used in the prior art for the support of the electrodes in the structure illustrated in Fig. 3. In this Fig. 3, there is the small opening 25 for the supporting hook for the cathode, the opening 26 in which is secured the standard 20 for the control grid, and the opening 2! in which is supported the standard 22 for the screen grid. The shaded part indicates the particles of material or condensed vapor that will gradually accumulate on the surface of the insulator exposed to the discharge path. In time, these particles will be sufiiciently close together for a charge of electricity to leak across the surface of the insulators by means of the conductive path provided by these particles from one or more of these standards to the others.

According to my invention, I utilize an insulating support that will prevent any such leakage charge across the surface of the insulator. The top insulator 23 preferably has the elongated form disclosed more particularly in Figs. 4 and 5. This insulator has a slot 28 extending from one edge parallel with the top and bottom and extending through the hole 29 for the support of the hook M for the cathode. Another slot 30 likewise extends from the opposite edge parallel with the top and bottomof the insulator through the opening 3| for the hook l4 supporting the upper portion of the cathode on the lefthand side of the electrode assembly. The insulator thus comprises a central solid portion 32 having an upper ledge 33 and a lower ledge 34 extending on one side of the central portion and a similar parallel extending upper ledge 35 and lower ledge 36 extending on the other side of the central portion.

The holes 29 and 3| for the cathode supporting hooks 14 have their openings 31 and 38 in the lower ledges 34 and 36 enlarged so that there will be no contact of the hook l4 against the sides of the lower ledge. On either side of the holes 29 and 3! for the cathode supports are holes 36 and 4G to rather closely embrace the sup porting standards is and 253 for the control grid in the upper ledges 33 and 35. These standards I!) and 2|] are preferably secured by welding small cross-wire M to the upper end of these standards where they project through the top of the insulating ledges 33 and 35. The openings 42 and 43 through the lower ledges 3t and 3% are enlarged as disclosed in Fig. 1 so that the standards If) and 26 make no contact therewith. Similarly, the standards 2! and 22 for the screen grid have a rather close-fitting opening 44 and 45 in the upper ledges 33 and 35 and a small crosswire 46 welded thereto. The openings il and 43 in the lower ledges 34 and 36 are enlarged so that there is no contact between the ledges and these standards.

Similarly the bottom insulator 24 has slots 49 and 50 corresponding to slots 28 and 30 in the upper insulator. The lower or outer ledges 5i and 52 correspond with the upper and outer ledges 33 and 35 of the upper insulator. Likewise the inner and upper ledges 53 and 5 of the lower insulator correspond with the ledges 34 and 36 of the upper insulator. The material of the insulators may be of porcelain or other ceramic material or material that does not conduct electricity. In case the material is such that there should be no undue strain of compression on the two ledges towards each other, I preferably utilize a sleeve 55 about each of the conducting standards 56 and 51 of the anode and secure the anode thereto. At the upper and lower portion of the conducting sleeves 55, I place spacers 58 to make contact with the inner ends of the ledges 34, 36, 53, and 54. The outer corresponding ledges have enlarged openings 59 and 6B which are duplicated, but not disclosed, in ledges 5i and 52. A metal sleeve 6i surrounds the standards 55 and 5'! and is welded thereto to hold the insulators firmly in place as disclosed.

The bottom insulator has an opening there through for the passage of the standard ll to the midpoint of the cathode. The upper insulator may have such an unused opening 62 therethrough if it is not desired to have a separate insulator formed or cast for the upper insulator. The particles of material and the metallic vapor will be deposited on the surface of the insulators facing the discharge path between the electrodes This deposit will be upon the inner faces of the ledges 34, 3t, 53, and 54. These ledges do not make contacts with the standards and hooks supporting the grids and the cathode. Accordingly, there will not be the deposit between the leads as illustrated in Fig. 3 because of the enlarged openings 31, 38, 42, 43, 4"! and 48 in the upper insulator and corresponding openings in the ledges 53 and 54 of the lower insulator 24. Some of the particles may pass through these openings and be deposited around the leads as illustrated in Fig. 2 on the inner surface of the ledge 35. The area of this deposit will be restricted by the area of the holes 38, 43, and 48 respectively shown. The lower ledge 36 will protect the intervening space and maintain free of deposited particles the surface. at 63 between the cathode support and the control grid and at 64 between the control grid and the screen grid. A similar protective action takes place at the other side of the insulator and also at the two sides of the bottom insulator.

As previously mentioned, the insulator may be made of various insulating materials and may be either cast, pressed, or molded into the form disclosed or slotted and drilled to form. The particular shape of the insulator may be varied to accommodate various numbers and various shapes of electrodes as desired. In fact, many modifications may be made in the form, nulnber and arrangement of the various elements disclosed in my preferred embodiment illustrated on the drawing, without departing from the spirit of the invention.

Accordingly, I desire only such limitations to be imposed on the following claims as is necessitated by the spirit and scope of the following claims.

I claim:

1. A discharge device comprising a plurality of electrodes having standards, a support therefor, comprising an insulator having parallel extending ledges and aligned openings for said standards in said ledges.

2. An insulator support for electrodes of a discharge device comprising a body having two parallel ledges, aligned openings in said ledges, the diameter of some of said aligned openings being different in one ledge than the other.

3. A discharge device comprising a plurality of electrodes having standards, a support therefor, comprising an insulator having parallel insulation ledges, aligned openings for the standards in said projections, some of said openings in the ledges nearer said electrodes having a clearance space about the standards passing therethrough.

4. A discharge device. comprising a cathode, grid and anode, standards for said cathode, grid and anode, and an insulator at each end of said electrodes supporting said standards, said insulators comprising a body having parallel ledges and aligned openings for the standards in said ledges.

5. A discharge device comprising a cathode, grid and anode, standards for said cathode, grid and anode, and an insulator at each end of said electrodes supporting said standards, said insulators comprising a body having parallel ledges and aligned openings for the standards in said ledges, said openings in the projections nearer the. electrode being too large to make contact with the cathode and grid standards.

6. A discharge device comprising a cathode, grid and anode, standards for said cathode, grid and anode, two insulators supporting the ends of said standards, each insulator having two parallel extending inner and outer ledges aligned with said electrodes and standards, aligned openings in said ledges for the standards, said cathode and grid standards being supported from the outer ledges of the insulators and the anode standards being supported from the inner ledges of said insulators.

7. A discharge device comprising a cathode, grid and anode, standards for said cathode, grid and anode, two insulators supporting the ends of said standards, each insulator having two parallel extending inner and outer ledges aligned with said electrodes and standards, aligned openings in said ledges for the standards, said cathode and grid standards being supported from the outer ledges of the insulators, and the anode standards being supported from the inner ledges of said insulators, said inner ledges having openings out of contact with the standards of the cathode and grid.

JOHN GLAUBER. 

